A multiplexing B de-multiplexing C forwarding D routing
63. In the following four descriptions about the relationship between the transport layer and the network layer, which one is not correct A The transport-layer protocol provides logical communication between hosts
B The transport-layer protocol provides logical communication between processes
C The services that a transport-layer protocol can provide are often constrained by the service model of the network-layer protocol D A computer network may make available multiple transport protocols 64. Suppose the following three 8-bit bytes: 01010101, 01110000, 01001100. What’s the 1s complement of the sum of these 8-bit bytes A 00010001 B
C 00010010 D
65. The following four descriptions about multiplexing and de-multiplexing, which one is correct
A A UDP socket is identified by a two-tuples consisting of a source port number and a destination port number.
B If two UDP segment have different source port number, they may be directed to the same destination process.
C If two TCP segments with different source port number, they may be directed to the same destination process.
D If two TCP segments with same destination IP address and destination port number, they must be the same TCP connection. 66. UDP and TCP both have the fields except ____. A source port number B destination port number C checksum D receive window
67. If we define N to be the window size, base to be the sequence number of the oldest unacknowledged packet, and next-seq-num to be the smallest unused sequence number, then the interval [nextseqnum,base+N-1] corresponds to packet that ____. A can be sent immediately
B have already been transmitted and acknowledged C cannot be used
D have been sent but not yet acknowledged
68. Which of the following about TCP is not correct A It is a connectionless protocol B Point-to-point protocol
C Reliable, in-order byte steam protocol D Pipelined protocol
69. Which of the following about TCP is not correct A It is a connectionless protocol B full duplex data transfer protocol C connection-oriented protocol D flow controlled protocol
70. The maximum amount of data that can be grabbed and placed in a segment is limited by the ____.
A Maximum segment size (MSS) B MTU
C Sequence number D Check sum
71. The MSS is typically set by first determining the length of the largest link-layer frame that can be sent by the local sending host (the so-called____), and then will fit into a single link-layer frame. A Maximum segment size (MSS) B MTU
C Sequence number D Check sum
72. The MSS is the maximum amount of ____layer data in the segment, not the maximum size of the TCP segment including headers. A Application B Transport C Networking D Link
73. Which of the following field is not used for connection setup and teardown
A Sequence number B TST C SYN D FIN
74. ____ is the byte stream number of first byte in the segment. A Sequence number B ACK number C Checksum
D port number
75. ____ is the byte sequence numbers of next byte expected from other side.
A Sequence number B ACK number C Checksum D port number
76. Because TCP only acknowledges bytes up to the first missing byte in the stream, TCP is said to provide ____ acknowledgements. A Cumulative B Selective C Single D Negative
77. Fast retransmit means in the case that ____ duplicate ACK-s are received, the TCP sender resend segment before timer expires. A 3 B 4 C 5 D 6
78. TCP____ means sender won’t overflow receiver’s buffer by transmitting too much, too fast. A Flow control B Congestion control C Reliable data transfer D Connection-oriented service
79. TCP provides flow control by having the sender maintain a variable called the ____.
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